1. Field of the Invention
The present invention relates to digital multimedia broadcasting (DMB), and in particular to managing digital broadcasting channels in a DMB system.
2. Discussion of the Related Art
High-quality digital audio devices, such as compact discs (CDs) and digital versatile discs (DVDs), have increased in acceptance and popularity throughout the world. Consequently, listeners of digital broadcasts have demanded that such broadcasts provide audio at quality that equals that of CDs and DVDs. Digital audio broadcasting (DAB) systems have been widely used to obviate limitations in the quality of audio available from typical amplitude modulation (AM) and frequency modulation (FM) broadcast services.
DAB is a technology that is currently implemented in various countries such as Europe, Canada, and the United States. A DAB system implements technology which differs from that of conventional AM and FM broadcasting systems, and is able to provide robust, high-quality, signals which are readily received by both stationary and mobile receivers.
In recent times, a variety of multimedia services include both audio and video data using a digital multimedia broadcasting (DMB) service. A typical DMB service can provide users with high-quality audio and video data. The Eureka-147 system has been developed for the above-mentioned DAB service, and has been utilized to provide content using DMB.
A single ensemble, which is one of the many types of broadcast signals in the DAB system, is composed of one or more services. A single service is composed of one or more service components. Individual sub-channels or fast information data channels (FIDCs) may be used for each of these service components.
Multiplex configuration information (MCI) identifies services multiplexed into the ensemble, service components contained in individual services, and position information of the service components. The MCI forms part of the main service channel (MSC), which is repeatedly broadcast and subsequently received by a receiving device, such as a terminal. The terminal utilizes the received MCI to interpret the MSC.
The term reconfiguration will be used herein to refer to a change in an ensemble structure of a received broadcast signal. Typically, the receiving terminal is readied for a change to a new ensemble prior to the actual reconfiguration process. This may be accomplished by transmitting new MCI (i.e., information regarding the reconfiguration) to the receiving terminal at a point of time prior to the actual occurrence of the reconfiguration process. As an example, the MCI may be broadcast to the receiving terminal about six seconds before the reconfiguration actually occurs.
During reconfiguration, one or more changes may occur. For instance, the reconfiguration may change the number of services that make up the ensemble, the structure of the service components, the configuration within an ensemble structure, and combinations thereof.
FIG. 1 depicts a reconfiguration in which the number of services within an ensemble structure is increased from three to four services. The original services include sports, movies, and radio. The reconfiguration provides for the addition of the news service.
FIG. 2 depicts a reconfiguration in which the number of services within an ensemble structure is decreased from three to two services. Another reconfiguration possibility would be for the number of services to remain the same, but the sub-channel which belongs to a particular service may be changed to another sub-channel. This channel switching may be performed for one or more of the services of the ensemble structure.
A user is typically unaware of changes to the ensemble structure until they are notified of the reconfiguration. The user therefore only realizes the addition or deletion of a service, resulting from received channel information, after changes in the structure of the ensemble has occurred. In addition, conventional techniques usually permit obtaining the relevant ensemble change information only when actively displaying a particular service. There is currently no viable technique for obtaining the relevant information when changing non-active configurations of the ensemble. Periodically performing fast information channel (FIC) decoding has previously been proposed to solve the problem. However, this solution requires performing FIC decoding in fade areas.